Epithelial-to-mesenchymal transition in ameloblastoma: focus on morphologically evident mesenchymal phenotypic transition.

The ameloblastoma is the most common and clinically significant odontogenic epithelial neoplasm known for its locally-invasive behaviour and high recurrence risk. Epithelial-to-mesenchymal transition (EMT) is a fundamental process whereby epithelial cells lose their epithelial characteristics and gain mesenchymal properties. EMT induction via transcription repression has been investigated in ameloblastoma. However, morphologically evident mesenchymal phenotypic transition remains ill-defined. To determine this, 24 unicystic (UA), 34 solid/multicystic (SA) and 18 recurrent ameloblastoma (RA) were immunohistochemically examined for three EMT-related mesenchymal markers, alpha smooth muscle actin (α-SMA), osteonectin and neuronal cadherin (N-cadherin). All three factors were heterogeneously detected in ameloblastoma samples (α-SMA, n=71/76, 93.4%; osteonectin, n=72/76, 94.7%; N-cadherin, n=24/76, 31.6%). In the tumoural parenchyma, immunoreactive cells were not morphologically distinct from their non-reactive cellular counterparts. Rather, α-SMA and osteonectin predominantly labelled the cytoplasm of central polyhedral > peripheral columnar/cuboidal tumour cells. N-cadherin demonstrated weak-to-moderate circumferential membranous staining in both neoplastic cell types and cytoplasmic expression in spindle-celled epithelium of desmoplastic amelobastoma. For all tumour subsets, α-SMA and osteonectin scored significantly higher in the stroma > parenchyma whilst α-SMA was overexpressed along the tumour invasive front > centre (p<0.05). Stromal N-cadherin scored higher in SA > UA and RA > UA (p<0.05). Other clinicopathological parameters showed no significant associations. Taken together, acquisition of mesenchymal traits without morphologically evident mesenchymal alteration suggests partial EMT in ameloblastoma. Stromal upregulation of these proteins in SA and RA implicates a role in local invasiveness.

Invadopodia proteins, cortactin, N-WASP and WIP differentially promote local invasiveness in ameloblastoma.

BACKGROUND: Cell migration and invasion through interstitial tissues are dependent upon several specialized characteristics of the migratory cell notably generation of proteolytic membranous protrusions or invadopodia. Ameloblastoma is a benign odontogenic epithelial neoplasm with a locally infiltrative behaviour. Cortactin and MMT1-MMP are two invadopodia proteins implicated in its local invasiveness. Other invadopodia regulators, namely N-WASP, WIP and Src kinase remain unclarified. This study addresses their roles in ameloblastoma. MATERIALS AND METHOD: Eighty-seven paraffin-embedded ameloblastoma cases (20 unicystic, 47 solid/multicystic, 3 desmoplastic and 17 recurrent) were subjected to immunohistochemistry for expression of cortactin, N-WASP, WIP, Src kinase and F-actin, and findings correlated with clinicopathological parameters. RESULTS: Invadopodia proteins (except Src kinase) and F-actin were widely detected in ameloblastoma (cortactin: n = 73/87, 83.9%; N-WASP: n = 59/87; 67.8%; WIP: n = 77/87; 88.5%; and F-actin: n = 87/87, 100%). Protein localization was mainly cytoplasmic and/or membranous, and occasionally nuclear for F-actin. Cortactin, which functions as an actin-scaffolding protein, demonstrated significantly higher expression levels within ameloblastoma tumoral epithelium than in stroma (P < 0.05). N-WASP, which coordinates actin polymerization and invadopodia-mediated extracellular matrix degradation, was overexpressed in the solid/multicystic subtype (P < 0.05). WIP, an upstream regulator of N-WASP, and F-actin were significantly upregulated along the tumour invasive front compared to tumour centres (P < 0.05). Except for males with cortactin overexpression, other clinical parameters (age, ethnicity and anatomical site) showed no significant correlations. CONCLUSIONS: Present results suggest that local invasiveness of ameloblastoma is dependent upon the migratory potential of its tumour cells as defined by their distribution of cortactin, N-WASP and WIP in correlation with F-actin cytoskeletal dynamics.

RANK, RANKL, and OPG in recurrent solid/multicystic ameloblastoma: their distribution patterns and biologic significance.

OBJECTIVES: To determine the distribution patterns of bone resorption regulators, receptor activator of nuclear factor κ-B (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG) in recurrent ameloblastoma (RAs) and to clarify their impact on the biologic behavior of these neoplasms. MATERIALS AND METHODS: Fifteen paraffin-embedded RA cases were subjected to immunohistochemistry for expression of RANK, RANKL, and OPG. RESULTS: The RANK-RANKL-OPG triad was heterogeneously detected in RA samples. RANK, essential for osteoclast differentiation, was strongly expressed in tumoral epithelium. Conversely, RANKL, an osteoclast activator, was markedly underexpressed, and protein localization was predominantly stromal. OPG, an osteoclastogenesis inhibitory factor, was detected in neoplastic epithelium more than in stroma, suggesting functional inactivation of RANKL. Most RA (n = 12/15; 80%) exhibited a bimolecular spatial expression pattern, the most common being RANK-positive/OPG-positive (n = 8/15; 53.3%). All three proteins showed no significant correlation with the clinical/histopathologic parameters in RA patients (P > .05). CONCLUSIONS: The RANK(+)/RANKL(low/-)/OPG(+) phenotype observed in RA suggests an altered local bone metabolism characterized by low bone resorptive activity in these recurrent tumors.

Comparative assessment of the interfacial soft and hard tissues investing implants and natural teeth in the macaque mandible.

OBJECTIVES: The aim of this study was to conduct a comparative qualitative and quantitative assessment of the interfacial soft and hard tissues investing implants and natural teeth. MATERIALS AND METHODS: The test sample consisted of six adult healthy male Macaca fascicularis with three-unit splinted crowns, each crown supported by an Ankylos screw-shaped titanium implant. These implants were placed in the mandibular premolar-second molar region, one side by an immediate-loading (IL) and the other by delayed-loading (DL) protocol. The animals were sacrificed after 3 months of functional loading. Another two monkeys with natural dentition served as controls. Nondecalcified sections were prepared for assessment of optical intensities (OI) under a confocal laser scanning microscope. RESULTS: In both the test (IL and DL) and control, the soft tissue complexes demonstrated a highly fluorescent keratinized layer and diminished cytoplasmic and enhanced membranous fluorescence in the remaining epithelium. Peri-implant mucosa was further characterized by an intense fluorescence at the junctional epithelium-implant interface and in the stromal mononuclear infiltrate. Connective tissue contact and periodontal ligament were weakly fluorescent. In hard tissues, a high fluorescence was observed in peri-implant woven bone and along the implant-bone interface. Mean OI was significantly higher in peri-implant woven bone than around teeth (P < 0.05). In the remaining soft and hard tissue complexes, no significant differences in mean OI between the test and control were observed (P > 0.05). CONCLUSIONS: Present findings suggest that peri-implant woven bone is highly mineralized, while the peri-implant and gingival mucosa share structural similarities. CLINICAL RELEVANCE: Optical intensities of interfacial tissues investing implants and teeth are related to their biological properties.

Intra-epithelially entrapped blood vessels in ameloblastoma.

BACKGROUND: The ameloblastoma is a benign but locally aggressive odontogenic neoplasm with a high recurrence rate. While significant progress has been made in our understanding regarding the role of tumoral vasculature relative to the diverse behavioral characteristics of this tumor, no attention has been paid to a distinct subset of blood vessels entrapped within its epithelial compartment. As vascular niches are known to influence tumoral growth, clarification of these vessels is important. The objectives of this study were to investigate the morphologic characteristics of intra-epithelially entrapped blood vessels (IEBVs) in ameloblastoma and to speculate on their relevance. MATERIALS AND METHOD: Here, we evaluated the frequency, microvessel density (MVD), morphology, and distribution pattern of IEBVs in 77 ameloblastoma of different subtypes based on their immunoreactivity for endothelial markers (CD34, CD31, CD105), vascular tight junction protein (claudin-5), pericyte [α-smooth muscle actin (α-sma)], and vascular basement membrane (collagen IV). RESULTS: IEBVs were heterogeneously detected in ameloblastoma. Their mean MVD (CD34 = 15.46 ± 7.25; CD31 = 15.8 ± 5.04; CD105 = 0.82 ± 0.51) showed no significant correlation with different subtypes, and between primary and recurrent tumors (P > 0.05). These microvessels may occur as single/clusters of capillary sprouts, or formed compressed branching/non-branching slits entrapped within the epithelial compartment, and in direct apposition with polyhedral/granular neoplastic epithelial cells. They expressed proteins for endothelial tight junctions (claudin-5-positive) and pericytes (α-sma-positive) but had deficient basement membrane (collagen IV weak to absent). Aberrant expression for CD34, CD31, and CD105 in tumor epithelium was variably observed. CONCLUSIONS: Although rare in occurrence, identification of IEBVs in ameloblastoma could potentially represent a new paradigm for vascular assessment of this neoplasm.

Podoplanin, E-cadherin, ß-catenin, and CD44v6 in recurrent ameloblastoma: their distribution patterns and relevance.

BACKGROUND: Ameloblastoma is a benign but locally infiltrative odontogenic epithelial neoplasm with a high risk for recurrence. Podoplanin, a lymphatic endothelium marker, putatively promotes collective cell migration and invasiveness in this neoplasm. However, its role in the recurrent ameloblastoma (RA) remains unclear. As morphological, signaling, and genetic differences may exist between primary and recurrent tumors, clarification of their distribution patterns is of relevance. MATERIALS AND METHODS: Podoplanin was examined immunohistochemically in conjunction with E-cadherin, ß-catenin, and CD44v6 in 25 RA. Immunostaining according to tumor area, cellular type, and location, and relationship of these proteins were analyzed. Findings were compared with 25 unrelated primary ameloblastomas (UPA). RESULTS: All four proteins were detected in RA and UPA samples. Expression rates for each protein were not significantly different between these two groups. RA demonstrated significant upregulation of podoplanin at the invasive front (P < 0.05), whereas upregulation of ß-catenin and CD44v6 and downregulation of E-cadherin at this site were not statistically significant (P > 0.05). Immunolocalization for all four proteins was predominantly membranous and less frequently cytoplasmic. Pre-ameloblast-like cells were podoplanin(+) /CD44v6(-), while stellate reticulum-like cells were podoplanin(-)/CD44v6(+). Acanthomatous, granular cell, and desmoplastic variants in both RA and UPA were podoplanin(-/low) but stained weak-to-moderate for E-cadherin, ß-catenin, and CD44v6. Stromal fibroblasts and lymph channels were variably podoplanin-positive. CONCLUSIONS: Podoplanin, ß-catenin, and CD44v6 upregulation at the tumor invasive fronts in RA and UPA supports a differential regulatory role by these molecules in mediating collective cell migration and local invasiveness. E-cadherin downregulation suggests altered cell adhesion function during tumor progression.

Differential expression of transcription factors Snail, Slug, SIP1, and Twist in ameloblastoma.

BACKGROUND: Epithelial-to-mesenchymal transition (EMT) via the mechanism of transcription repression is a crucial process for the induction of invasiveness in many human tumors. Ameloblastoma is a benign odontogenic epithelial neoplasm with a locally infiltrative behavior. Twist, an EMT promoter, has been implicated in its invasiveness. The roles of the other transcription factors remain unclarified. MATERIALS AND METHODS: Four transcription factors, namely Snail, Slug, SIP1, and Twist, were examined immunohistochemically in 64 ameloblastoma [18 unicystic (UA), 20 solid/multicystic (SA), 4 desmoplastic (DA), and 22 recurrent (RA)]. RESULTS: All four transcription factors were differentially expressed in ameloblastoma [Snail: n = 60/64 (94%); Slug: n = 21/64 (33%); SIP: n = 18/64 (28%); Twist: n = 26/64 (41%)] (P < 0.05). Their distribution patterns were heterogeneous and were not significantly different between the tumor invasive front and central area (P > 0.05). Intracellular protein localization was predominantly nuclear for Snail, cytoplasmic>nuclear for Slug and SIP1, and cytoplasmic/nuclear for Twist. Overexpression of Snail in most subsets (UA = 18/18; SMA = 19/20; DA = 4/4; RA = 19/22) compared with the other transcription factors (P < 0.05) and selective expression for Slug, SIP1, and Twist in squamous/keratinous foci and at sites of epithelial cystic degeneration were among the main observations made. Stromal cells surrounding immunoreactive tumor cells tended to stain positive. CONCLUSIONS: Present findings suggest that these transcription factors probably play differential roles in mediating local invasiveness in ameloblastoma. Overexpression of Snail in most subsets suggests that this molecule is most likely the prototype transcription factor involved in inducing EMT in the ameloblastoma.

Identifying factors associated with diagnostic concordance/discordance in oral lichen planus.

PURPOSE: To identify factors associated with concordance and discordance between clinical and histopathologic diagnoses of oral lichen planus lesions. MATERIALS AND METHODS: A retrospective analysis was conducted on all study cases derived from archival oral pathology reports generated from all cases of oral lichen planus accessioned by the Faculty of Dentistry, University of Malaya. These study cases were diagnosed from January 1980 through December 2010. Predictor variables were diagnosis year, demographics, experience of the examiner, clinical appearance and diagnosis, and final histopathologic diagnosis; these were recorded for each study case. The outcome variable was agreement between the clinical and histopathologic diagnoses, and this was classified as concordant or discordant. Descriptive statistics and multiple linear regression analyses were computed to identify associations between predictors and outcomes. Statistical significance was set at P ≤ .05. RESULTS: The sample was composed of 441 study cases with 593 oral mucosal lesions that met the inclusion criteria. The mean age of the sample was 47.5 ± 13.07 years (range, 12 to 82 yr) and 64.4% were female. The mean concordance was 83.2%. Diagnosis year and demographics showed no influence on concordance or discordance. The multiple linear regression model included experience of the examiner, clinical appearance and diagnosis, and final histopathologic diagnosis (R(2) = 0.82). Except for experience of the examiner (P = .12), clinical appearance and diagnosis and final histopathologic diagnosis were the variables statistically associated with concordance (P ≤ .01). CONCLUSIONS: The present results suggest that concordance is governed primarily by the clinical appearance and diagnosis of the lesion and the final histopathologic diagnosis.

Cementum status in natural teeth opposing implant-borne bridgework in Macaca fascicularis.

OBJECTIVE: The objective of this study was to investigate the cementum status in natural teeth opposing implant-supported bridgework. METHODS: Maxillary premolars and molars opposing immediate-loading (IL) and delayed-loading (DL) mandibular implant-supported bridgework in 4 Macaca fascicularis were harvested after 3 months of functional loading. Another 2 monkeys without mandibular fixed prostheses served as control. The cervical (CCW) and apical cementum width (ACW), and resorption craters (RCs) were measured. RESULTS: No significant differences were observed between test and control groups for mean CCW (control = 26.79 ± 3.28, IL = 21.29 ± 9.12, and DL = 20.32 ± 5.65 µm) and for ACW (control = 937.97 ± 353.74, IL = 955.26 ± 720.05, and DL = 750.56 ± 517.26 µm) (P > .05). In test and control monkeys, RCs were uncommon and showed no significant differences in width (control = 0.71 ± 0.38, IL = 1.02 ± 0.49, DL = 0.85 ± 1.02 mm) and depth (control = 0.15 ± 0.07, IL = 0.25 ± 0.40, DL = 0.22 ± 0.15 mm) (P > .05). CONCLUSIONS: Present findings suggest that implant-supported bridgework does not produce any adverse effects on the cementum of opposing natural teeth after 3 months of functional loading.

Ameloblastoma of the jaws: a retrospective analysis of 340 cases in a Malaysian population.

PURPOSE: Ameloblastoma of the human jaw is an uncommon but clinically significant odontogenic epithelial neoplasm. The aim was to analyze the clinicopathologic characteristics of ameloblastoma in a Malaysian population. MATERIALS AND METHODS: This is a retrospective study (1993 through 2008) of consecutive ameloblastoma cases accessioned in 2 main oral pathology diagnostic centers: the Unit of Stomatology, Institute for Medical Research and the Department of Oral Pathology, Oral Medicine, and Periodontology, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia. Data on patient demographics, tumor location, symptomology, duration, radiographic appearance, preoperative diagnosis, clinicopathologic subtypes, treatment, and recurrence were analyzed. RESULTS: Three hundred forty cases of ameloblastoma were reviewed. These were from 197 male patients (57.9%) and 143 female patients (42.1%), with a male-to-female ratio of 1.4:1. A wide age range (7 to 85 years), mean onset age of 30.3 ± 16.3 years, and peak incidence in the second decade of life were recorded. Most were mandibular tumors (n = 311/340, 91.5%). These consisted of 95 (28%) unicystic ameloblastomas, 221 (65%) solid/multicystic ameloblastomas, 22 (6.4%) desmoplastic ameloblastoma, and 2 (0.6%) peripheral ameloblastomas. Unicystic ameloblastoma (41.1%) and solid/multicystic ameloblastoma (52.0%) mostly affected Malays patients, whereas desmoplastic ameloblastoma (59.1%) was prevalent in Chinese patients. Unicystic ameloblastoma (56.8%) and solid/multicystic ameloblastoma (47.1%) occurred predominantly in the body and posterior mandible, whereas desmoplastic ameloblastoma (36.4%) preferentially involved the anterior jaw segment. Most tumors presented as multilocular radiolucencies (36.8%). Enucleation (n = 42/92, 45.7%) was the treatment of choice. About 18 cases (13.3%) presented with recurrence. CONCLUSIONS: Because ameloblastoma subsets differ in their biologic behavior, the present data are significant as baseline references for clinicians and pathologists.

Differential expression of canonical and non-canonical Wnt ligands in ameloblastoma.

BACKGROUND: Canonical and non-canonical Wnt signaling pathways modulate diverse cellular processes during embryogenesis and post-natally. Their deregulations have been implicated in cancer development and progression. Wnt signaling is essential for odontogenesis. The ameloblastoma is an odontogenic epithelial neoplasm of enamel organ origin. Altered expressions of Wnts-1, -2, -5a, and -10a are detected in this tumor. The activity of other Wnt members remains unclarified. MATERIALS AND METHODS: Canonical (Wnts-1, -2, -3, -8a, -8b, -10a, and -10b), non-canonical (Wnts-4, -5a, -5b, -6, 7a, -7b, and -11), and indeterminate groups (Wnts-2b and -9b) were examined immunohistochemically in 72 cases of ameloblastoma (19 unicystic [UA], 35 solid/multicystic [SMA], eight desmoplastic [DA], and 10 recurrent [RA]). RESULTS: Canonical Wnt proteins (except Wnt-10b) were heterogeneously expressed in ameloblastoma. Their distribution patterns were distinctive with some overlap. Protein localization was mainly membranous and/or cytoplasmic. Overexpression of Wnt-1 in most subsets (UA = 19/19; SMA = 35/35; DA = 5/8; RA = 7/10) (P < 0.05), Wnt-3 in granular cell variant (n = 3/3), and Wnt-8b in DA (n = 8/8) was key observations. Wnts-8a and -10a demonstrated enhanced expression in tumoral buddings and acanthomatous areas. Non-canonical and indeterminate Wnts were absent except for limited Wnt-7b immunoreactivity in UA (n = 1/19) and SMA (n = 1/35). Stromal components expressed variable Wnt positivity. CONCLUSION: Differential expression of Wnt ligands in different ameloblastoma subtypes suggests that the canonical and non-canonical Wnt pathways are selectively activated or repressed depending on the tumor cell differentiation status. Canonical Wnt pathway is most likely the main transduction pathway while Wnt-1 might be the key signaling molecule involved in ameloblastoma tumorigenesis.

Subcutaneous reactions and degradation characteristics of collagenous and noncollagenous membranes in a macaque model.

BACKGROUND: collagenous and noncollagenous membranes have been investigated in many animal systems but their effects in the macaque model are unknown. OBJECTIVE: to determine subcutaneous cellular reactions and degradation characteristics following implantation of collagenous and noncollagenous membranes in a macaque model. METHODS: six adult male Macaca fascicularis, aged above 7 years, were used. Six commercially available collagenous (Bio-Gide [BG], Tissue Fleece [TFL] TissueFoil E forte [TFO], Lycoll [LC], Surgicoll [SG] and Tutodent [TU]) and two noncollagenous (Tabotamp [TA] and Gelita-Tampon [GT]) membranes (size 2 × 2 cm each) were implanted in unconnected subcutaneous pouches in the monkey's back and wounds were allowed to heal by primary intention. The total sample size for each membrane was six. Two monkeys were sacrificed for each experimental period of 4, 14 and 28 days. Explanted specimens were prepared for histologic and histomorphometric analysis. Digitized images of implant sites were systematically sampled using an Image Analyzer with a grid containing 35 intersection points. Four parameters were quantified: membrane degradation, foreign body reaction, tissue organization and vascularization. RESULTS: biodegradation rate and vascularization scored higher in collagenous than in noncollagenous membranes. Except for TFL and TU, the remaining six membranes showed a moderately intense foreign body reaction at week 2. Tissue organization was initiated early in four out of six collagenous (TFL>LC>SG>TFO>BG>TU) compared with one of two noncollagenous (TA>GT) membranes. CONCLUSIONS: the results suggest that differences in membrane structure and composition underlie their different cellular reactions and degradation characteristics.

Notch4 overexpression in ameloblastoma correlates with the solid/multicystic phenotype.

OBJECTIVE: Notch signaling has been implicated in cell fate decisions during odontogenesis and tumorigenesis of some odontogenic neoplasms; however, its role in solid/multicystic (SA), unicystic (UA), and recurrent (RA) ameloblastoma remains unclear. The aim of this study was to determine Notch receptor and ligand expressions in these subtypes and to speculate on their significance. METHODS: Notch receptors (Notch1, 2, 3, 4) and ligands (Jagged1, 2, and Delta1) were examined immunohistochemically in SA (n = 23), UA (n = 22), and RA (n = 19). RESULTS: Notch4 overexpression in SA (n = 19/23; 82.6%) compared with UA (n = 1/22; 4.5%) or RA (n = 10/19; 52.6%) (P < .05) suggests positive correlation between Notch4 signaling and ameloblastomas with a solid/multicystic phenotype. Ligand (Jagged1 and Delta1) underexpression compared with their receptors (Notch1, 3, 4) (P < .05) and nonreactivity for Notch2 and Jagged2 in all 3 subsets suggests that ameloblastoma epithelium belongs to an earlier stage of differentiation (equivalent to inner enamel epithelium of developing tooth germ) before lineage commitment. CONCLUSION: Present findings suggest that Notch signaling molecules may play differing roles in the acquisition of different ameloblastoma phenotypes.

Differential expression of Notch receptors and their ligands in desmoplastic ameloblastoma.

BACKGROUND: In mammals, the Notch gene family encodes four receptors (Notch1-4), and all of them are important for cell fate decisions. Notch signaling pathway plays an essential role in tooth development. The ameloblastoma, a benign odontogenic epithelial neoplasm, histologically recapitulates the enamel organ at bell stage. Notch has been detected in the plexiform and follicular ameloblastoma. Its activity in the desmoplastic ameloblastoma is unknown. METHOD: Notch1-4 and their ligands (Jagged1, Jagged2 and Delta1) were examined immunohistochemically in 10 cases of desmoplastic ameloblastoma. RESULTS: Ameloblastoma tumor epithelium demonstrated positive expression for Notch1 (n = 5/10), Notch3 (n = 8/10), Notch4 (n = 10/10), Jagged1 (n = 6/10) and Delta1 (n = 5/10), but no reactivity for Notch2 (n = 10/10) and Jagged2 (10/10). Expression patterns were distinct with some overlap. Positive activity was detected largely in the cell membrane and cytoplasm of peripheral and central neoplastic epithelial cells, and sometimes in the nucleus. Staining score was highest for Notch4. Stromal components namely endothelial cells and fibroblasts showed overexpression for Notch4 but were mildly or non-reactive for the other Notch members and their ligands. CONCLUSIONS: These findings suggest that Notch receptors and their ligands may play differing roles during the development of the desmoplastic ameloblastoma with Notch4 probably playing a greater role in the acquisition of tissue-specific cellular characteristics in the desmoplastic ameloblastoma.

Heparanase and vascular endothelial growth factor expression in the progression of oral mucosal melanoma.

Oral mucosal melanoma is an aggressive neoplasm with poor prognosis. Heparanase is an endo-beta-d-glucuronidase, which cleaves heparan sulphate chains. The vascular endothelial growth factor (VEGF) is the most potent angiogenic mitogen and interaction with its receptor (VEGFR) has been associated with angiogenesis. We investigated the expression of these molecules in the progression of oral mucosal melanoma. Immunohistochemistry was carried out in 15 oral melanotic macules and 19 oral melanomas using heparanase, VEGF, VEGFR-2, CD34 and Ki-67. Microvessel density was determined and subjected to statistical analysis. Heparanase and VEGFR-2 were not expressed in the oral melanotic macule. Atypical melanocytes and melanoma cells expressed heparanase, VEGF and VEGFR-2. An intense expression was noted in the early invasive phase, which marks the crucial transition from in situ to the invasive phase. In the invasive component, heparanase was intense but selective in the invasive fronts and at the periphery of nests unlike the extensive expression of VEGF and VEGFR-2. However, hot spots were only observed at the periphery of the nests. In conclusion, melanoma cells expressed heparanase, VEGF and VEGFR-2. The coexpression of these molecules in atypical melanocytes and melanoma cells suggests their function in cell migration and invasion. Moreover, the intense expression in the crucial transition from in situ to the invasive phase suggests their role in the progression of the tumor. The role of VEGF and VEGFR-2 in angiogenesis was evident only at the periphery of the nests in the invasive components.

An updated clinical and epidemiological profile of the adenomatoid odontogenic tumour: a collaborative retrospective study.

BACKGROUND: Adenomatoid odontogenic tumour (AOT) is a benign odontogenic jaw lesion. The aim of this study was to update the biological profile of AOT. MATERIAL AND METHODS: Cases published in the literature and cases in files of co-authors were included. RESULTS: 550 new cases were retrieved, and of a total of 1082 cases analysed, 87.2% were found in the second and third decades. The M:F ratio was 1:1.9. 70.8% were of the follicular variant (extrafollicular: 26.9%, peripheral: 2.3%). 64.3% occurred in the maxilla. 60% of follicular AOTs were associated with unerupted canines. Nineteen cases of AOT (2.8%, M:F ratio was 1:1.4) were associated with embedded third molars. Twenty-two peripheral AOTs (2.3%, M:F ratio was 1:5.3) were recorded. The relative frequency (RF) of AOT ranged between 0.6% and 38.5%, revealing a considerably wider AOT/RF range than hitherto reported (2.2-7.1%). CONCLUSIONS: This updated review based on the largest number of AOT cases ever presented, confirms the distinctive, although not pathognomonic clinicopathological profile of the AOT, its worldwide occurrence, and its consistently benign behaviour.

Osteoma of the condyle as the cause of limited-mouth opening: a case report.

Osteoma is a benign tumour consisting of mature bone tissue. It is an uncommon lesion that occurs mainly in the bones of the craniofacial complex. Only a few cases involving the condylar process have been reported. An osteoma of the left condyle causing limited mouth-opening in a 32-year-old Malaysian Chinese female is reported here to alert the practitioner to consider this lesion as a diagnostic possibility in instances of trismus or limited-mouth opening.

Osteosarcoma presenting as an aggressive nodular mass in the region of the mandible.

Osteosarcomas are highly malignant neoplasms of bone that are challenging to diagnose. These neoplasms often show atypical behavior. In the initial phase they may present as nondescript bony swellings with an indolent growth rate, only to become overtly aggressive and malignant towards the later phase of the disease. Similarly, the histological growth pattern of this neoplasm can be quite diverse, presenting with areas that mimic benign myofibroblastic tumors, giant cell granulomatous conditions and partial encapsulation. The final diagnosis of an osteosarcoma is often reached after thorough sampling and examination of multiple biopsy specimens. All these clinical features and histological diagnostic difficulties were encountered in a case of osteosarcoma affecting the right mandible of a 62-year-old Chinese woman described here. The diagnostic lessons accrued from this case are discussed.

Oral candidosis in non-Hodgkin's lymphoma: a case report.

Though oral candidosis is an opportunistic fungal infection that commonly affects immunocompromised patients, little is known of its occurrence as a complication of Non-Hodgkin's lymphoma. This paper reports a case of oral candidosis in a 20-year-old Indonesian woman with this lymphoproliferative disease. She presented with acute pseudomembranous candidosis on the dorsum and lateral borders of the tongue, bilateral angular cheilitis and cheilocandidosis. The latter is a rare clinical variant of oral candidosis, and the lesions affecting the vermilion borders presented as an admixture of superficial erosions, ulcers and white plaques. Clinical findings were confirmed with oral smears and swabs that demonstrated the presence of hyphae, pseudohyphae and blastospores, and colonies identified as Candida albicans. A culture from a saline rinse was also positive for multiple candidal colonies. Lip and oral lesions were managed with Nystatin. The lesions regressed with subsequent crusting on the lips, and overall reduction in oral thrush. As Non-Hodgkin's lymphoma is a neoplastic disease that produces a chronic immunosuppressive state, management of its oral complications, including those due to oral candidosis, is considered a long-term indication.

Odontogenic keratocyst with dentinoid formation.

Although rare, hard tissue deposits, namely dystrophic calcifications and cartilage, have been reported to occur in the connective tissue wall of the odontogenic keratocyst. However, dentinoid formation has not been previously documented. A case involving the left mandibular premolar-molar region in a 37-year-old Malay male is described here along with a brief review on the reported prevalence of hard tissue deposits in the odontogenic keratocyst. Differential diagnosis of this case from other dentinoid-forming odontogenic cysts and tumors-notably calcifying odontogenic cyst, odontoma, ameloblastic fibro-odontoma, central odontogenic fibroma and adenomatoid odontogenic tumor that may present with dentin/dentinoid formation-is discussed.